For a .NET application that calls ElasticSearch via NEST, I found the odd issue that the query via NEST always returns 0 documents, while - if I extract the underlying query and call ES directly with it via REST - I do successfully get back documents. Given that it's the same query I don't understand why the behaviour differs.

The mappings in ES look like this:

"mappings": {
    "properties": {
        "categoryId": {
            "type": "keyword"
        },
        "categoryName": {
            "type": "text"
        },
        "facilityId": {
            "type": "keyword"
        },
        "locationId": {
            "type": "keyword"
        },
        "isVisible": {
            "type": "boolean",
            "null_value": false
        },
        "location": {
            "type": "geo_point"
        },
        "name": {
            "type": "text"
        }
    }
},

The query via NEST:

        response = await _client.SearchAsync<ResultLocation>(
            s => s
                .Index(indexName)
                .Size(DefaultReturnBatchSize)
                .Query(q =>
                    q.Bool(b => b.Must(
                        m => m.Term(d => d.IsVisible, true),
                        m => m.GeoDistance(gd => gd
                            .Field(dl => dl.Location)
                            .Location(latitude, longitude)
                            .Distance(distance, DistanceUnit.Meters))
                    ))
                )
        );

If I'm outputting the used/generated query from NEST to logs, this results in the following query:

{
  "query": {
    "bool": {
      "must": [
        {
          "term": {
            "isVisible": {
              "value": true
            }
          }
        },
        {
          "geo_distance": {
            "distance": "50000000m",
            "location": {
              "lat": 52.553,
              "lon": 13.358
            }
          }
        }
      ]
    }
  },
  "size":200
}

If I'm calling ElasticSearch via REST with that query then I successfully get back documents, just not via the C# app and NEST.

I quadruple-checked that I'm indeed calling the same ES instance and the same instance.